Breasts Cleavage Girl

Lingerie has long been designed to emphasize cleavage. The tight lacing of corsets worn in the 19th and early 20th centuries emphasized both cleavage and the size of the bust and hips. Ball or evening gowns especially were designed to display and emphasize the décolletage. More recently, after corsets became unfashionable, brassieres and padding have served to project, display and emphasize the breasts, as has breast augmentation surgery.
Cleavage theory
British zoologist and ethologist Desmond Morris theorizes that cleavage is a sexual signal that imitates the image of the cleft between the buttocks, which according to Morris in The Naked Ape is also unique to humans, other primates as a rule having much flatter buttocks.